Neuropathy, also known as peripheral neuropathy, is an inflammation, injury, or degeneration of any nerve outside of the central nervous system. These nerves, known as the peripheral nerves, help the muscles to contract (motor nerves) and allow a range of sensations to be felt (sensory nerves). Peripheral nerves also help control some of the involuntary functions of the autonomic nerves, which regulate the sweat glands, blood pressure, and internal organs. Unfortunately, peripheral nerves are fragile and easily damaged. The symptoms of neuropathy depend upon the cause and on which nerve, or nerves, are involved.
In cancer patients, neuropathy may be a consequence of certain chemotherapy drugs, the cancers themselves, or other diseases and medications. If the sensory nerves are involved, the symptoms may include pain, numbness and tingling, burning, or a loss of feeling. If the motor nerves are affected, there may be weakness or paralysis of the muscles that control those nerves. These symptoms may begin gradually. Depending upon the specific nerves involved, symptoms can range from mild tingling or numbness in the fingers or toes to severe pain in the hands or feet. Patients may also describe these symptoms as burning, prickling, or pinching. Some patients report that the skin is so sensitive that the slightest touch is agonizing. They may also experience heaviness or weakness in the arms and legs. As neuropathy increases in severity, patients might have an unsteady gait and can have difficulty feeling the floor beneath them. Those with autonomic neuropathy might experience dizziness, constipation, difficulty urinating, impotence, vision changes, and hearing loss.
Neuropathy occurs in cancer patients for a number of reasons. The cancer itself may be infiltrating the nerves. Patients may have other diseases such as diabetes, nutritional imbalances, alcoholism, and kidney failure, which may also cause neuropathy. It is important for the physician to distinguish which factor is responsible, so the appropriate treatment can be initiated. The most common cause in cancer patients, however, is chemotherapy drugs. Neuropathy occurs in approximately 10-20% of cancer patients receiving chemotherapy. The most common chemotherapy drugs that cause neuropathy include:
- platinum compounds (e.g., cisplatin , carboplatin)
- taxanes (e.g., docetaxel and paclitaxel )
The following chemotherapy agents can also cause neuropathy, but the incidence is relatively small compared to the prior ones listed. These include:
- cytosine Arabinoside (Ara C or cytarabine );
Not long ago, few options were available to prevent or stop the progress of peripheral neuropathy. Treatments are now available that can halt the development of chemotherapy-caused neuropathy or at least diminish its effects.
The only effective preventive therapy is the use of amifostine (Ethyol). Some of the side effects of this medication include temporary low blood pressure, and nausea and vomiting . Patients should have adequate fluid intake before and during the 15-minute intravenous administration of amifostine. Blood pressure readings should be taken every five minutes during the infusion. Chemotherapy is administered shortly after giving the amifostine so that the maximum amount of the drug is in the cells before the chemotherapy is started.
If neuropathy does develop, it may be necessary to discontinue the suspected chemotherapy drug causing it. Administration of amifostine may reverse the neuropathy or lessen its symptoms.
A variety of medications are available that can ease symptoms for those suffering from neuropathy. These medications include:
- Pain relievers. Pain medicines available over-the-counter, such as acetaminophen (Tylenol), and non steroidal anti-inflammatory drugs (NSAIDs) such as aspirin and ibuprofen (Advil, Motrin IB, Nuprin), can help to alleviate mild symptoms. For more severe symptoms, the physician may recommend a prescription NSAID.
- Tricyclic antidepressants. Certain antidepressant medications, including amitriptyline (Elavil), nortriptyline (Pamelor), desipramine (Norpramin) and imipramine (Tofranil), can help with mild to moderate symptoms.
- Antiseizure medications. Certain drugs intended to treat epilepsy, such as carbamazepine (Tegretol) and phenytoin (Dilantin), can be effective in treating jabbing, shooting pain.
- Other drugs. Mexiletine (Mexitil), a drug normally used to treat irregular heart rhythms, may help to relieve burning pain.
The physician or pharmacist should be consulted regarding potential side effects or interactions with other medications.
Alternative and complementary therapies
Several other drug-free techniques can be helpful in providing pain relief. These are frequently used in conjunction with medication. These include:
- Biofeedback. This therapy uses a special machine to teach the patient how to control certain responses that can reduce pain.
- Transcutaneous electronic nerve stimulation (TENS). The physician may prescribe this treatment that may prevent pain signals from reaching the brain. It is generally more effective for acute pain than chronic pain.
- Acupuncture. This may be effective for chronic pain, including the pain of neuropathy.
- Hypnosis. The patient under hypnosis typically receives suggestions intended to decrease the perception of pain.
- Relaxation techniques. These techniques can help decrease the muscle tension that aggravates pain. They may include deep-breathing exercises, visualization, and meditation.
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— "Nursing Management of Peripheral Neurotoxicity and Quality of Life Concerns." Oncology Nursing Society Online Education. 28 June 2001. <http://nt.ons.org/ONS/education/online/neurotoxicities/content/text_topic4.htm>.
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Deanna Swartout-Corbeil, R.N.
Peripheral nervous system
—The portion of the nervous system outside of the central nervous system.
Autonomic nervous system
—The part of the nervous system that controls involuntary bodily functions.
—neuropathic (newr-oh-path-ik) adj.